imac alsa overdrive

[stereo]

it's much too loud. even if its one singel point over zero. any ideas?

[stereo]

i looked a bit around and found this.
setmixer -V
gives
root@ubu:/home/stereo # setmixer -V
vol - 0,0
speaker - 0,0
line - 100
mic - 100
cd - 100
igain - 0,0

but i can't change the line-output down to 50. the mixer seems dead in that position
setmixer vol -50
does it, but
setmixer line -50
does nothing

it's a pitty, anybody with similar problems?
i have an imac 350 slot-loading blueberry

thanks
stereo